A new, transportable ergometer for the measurement of musculotendinous stiffness during wrist flexion.

We present here a new, dedicated mechanical device for monitoring quick-release movements of the wrist. The ergometer was designed to easily assess musculotendinous properties during wrist flexion. Maximal voluntary contractions (MVC) and quick-release (QR) movements during wrist flexion were performed on 14 subjects. A validation of the ergometer, using a test-retest methodology, was performed to assess its reliability and sensitivity. The device has been technically and biomechanically validated in a range of situations, including inertia measurement (mean inertia was found 0.0119+/-0.0012 N m s(2) rad(-1)) and appearance of the unloading reflex. Our results indicate that the device provides highly reliable, sensitive evaluation of wrist muscle stiffness (intraclass correlation coefficient for inertia, maximal voluntary contraction and stiffness index were 0.873, 0.994 and 0.930, respectively). Its portability facilitates measurement of the influence of repetitive, occupational activity on the musculotendinous complex of the wrist flexors.     

The organization of synaptic interconnections in the laminae of the dorsal lateral geniculate nucleus of the cat

Summary Four axon types occur in the lateral geniculate nucleus. Two contain vesicles with mainly round profiles and these are distinguished from each other by their size, the appearance of their contents and by the types of contact they make. The larger RLP axons are interpreted as retinogeniculate and the smaller RSD axons as corticogeniculate fibers. The other two axon types contain many irregular or flattened vesicles and these F axons are regarded as two types of intrageniculate fiber.In laminae A and A 1 encapsulated synaptic zones form around grape-like dendritic appendages. These zones contain all axon types, but RSD axons are rare. Interstitial zones lie between the encapsulated zones and contain synapses formed by many RSD axons, some F and few RLP axons. The interstitial zones continue into the central interlaminar nucleus which forms a narrow band containing no encapsulated zones and few RLP axons. Lamina B contains relatively small RLP axons, very many RSD axons and only a few small encapsulated zones.Axosomatic junctions are rare throughout the nucleus. Axo-axonal junctions occur in all laminae but mostly in the encapsulated zones; the postsynaptic element is always an F axon, RLP or RSD axons generally form the presynaptic element.Supported by Grant NB 06662 from the USPHS. The skillful technical assistance given by Mrs. E. Langer during the course of this work is gratefully acknowledged.     

ZmEsr, a novel endosperm-specific gene expressed in a restricted region around the maize embryo

A novel endosperm-specific gene named Esr (e mbryo s urrounding r egion) has been isolated by differential display between early developmental stages of maize endosperms and embryos. It is expressed in a restricted region of the endosperm, surrounding the entire embryo at early stages (4 to 7 days after pollination, DAP) and ever-decreasing parts of the suspensor at subsequent stages. The expression starts at 4 DAP and is maintained until at least 28 DAP. A minimum of three Esr genes are present in the maize genome and at least two of them map to the short arm of chromosome 1 at position 56. The Esr genes contain no introns and show no significant nucleotide or amino acid sequence homologies to sequences in the databases. The open reading frames encode basic proteins of 14 kDa with presumptive signal peptides at their N-termini followed by a hypervariable and a conserved region. The gene product may play a role in the nutrition of the developing embryo or in the establishment of a physical barrier between embryo and endosperm.     

The development of the retinogeniculate pathways in normal and albino ferrets

The retinogeniculate pathways of normal and albino ferrets have been studied with horseradish peroxidase and tritiated proline used as axonal markers. The uncrossed retinogeniculate projection of adult albino ferrets is abnormally small and occupies only a fraction of the geniculate area normally occupied by uncrossed afferents. The crossed pathway is correspondingly expanded, occupying almost the entire nucleus. The geniculate laminae in the albino ferret are abnormal, showing abnormal fusions between layers receiving crossed input and abnormal discontinuities next to the small cell islands receiving uncrossed afferents. In early development, retinofugal fibres can be labelled within the optic tracts on the 28th intrauterine day and a few crossed fibres can be traced into the lateral geniculate nucleus. At this stage, the uncrossed component is extremely small in normal and albino animals and cannot be traced beyond the tract. By day 32 retinal fibres are invading the lateral geniculate nucleus bilaterally, the invasion by the crossed component being significantly more advanced than that by the uncrossed component. The uncrossed pathway of the albinos is already abnormal in terms of its size, in terms of the position it occupies in the optic tract, and in terms of its limited invasion of the lateral geniculate nucleus. The abnormally reduced size of the uncrossed component appears earlier than the abnormal segregation of the retinogeniculate terminals, suggesting that the primary action of the albino gene upon central visual pathways is prechiasmatic. At postnatal stages (41 days after conception and older) the normal, gradual withdrawal of the uncrossed fibres from the monocular segment, and the separation of crossed from uncrossed retinogeniculate terminal arbors is significantly delayed in the albinos. The uncrossed retinogeniculate terminals are abnormally sparse initially and become distributed in an abnormal, interrupted pattern as development proceeds. The abnormal pattern of geniculate lamination appears to be secondary to the abnormal distribution of retinogeniculate afferents.     

Variation in Specificity of HIV Rapid Diagnostic Tests over Place and Time: An Analysis of Discordancy Data Using a Bayesian Approach

Background

Recent trends to earlier access to anti-retroviral treatment underline the importance of accurate HIV diagnosis. The WHO HIV testing strategy recommends the use of two or three rapid diagnostic tests (RDTs) combined in an algorithm and assume a population is serologically stable over time. Yet RDTs are prone to cross reactivity which can lead to false positive or discordant results. This paper uses discordancy data from Médecins Sans Frontières (MSF) programmes to test the hypothesis that the specificity of RDTs change over place and time.

Methods

Data was drawn from all MSF test centres in 2007-8 using a parallel testing algorithm. A Bayesian approach was used to derive estimates of disease prevalence, and of test sensitivity and specificity using the software WinBUGS. A comparison of models with different levels of complexity was performed to assess the evidence for changes in test characteristics by location and over time.

Results

106, 035 individuals were included from 51 centres in 10 countries using 7 different RDTs. Discordancy patterns were found to vary by location and time. Model fit statistics confirmed this, with improved fit to the data when test specificity and sensitivity were allowed to vary by centre and over time. Two examples show evidence of variation in specificity between different testing locations within a single country. Finally, within a single test centre, variation in specificity was seen over time with one test becoming more specific and the other less specific.

Conclusion

This analysis demonstrates the variable specificity of multiple HIV RDTs over geographic location and time. This variability suggests that cross reactivity is occurring and indicates a higher than previously appreciated risk of false positive HIV results using the current WHO testing guidelines. Given the significant consequences of false HIV diagnosis, we suggest that current testing and evaluation strategies be reviewed.     

Involvement of Autonomic Nervous Activity Changes in Gastroesophageal Reflux in Neonates during Sleep and Wakefulness

Background

It has been suggested that disturbed activity of the autonomic nervous system is one of the factors involved in gastroesophageal reflux (GER) in adults. We sought to establish whether transient ANS dysfunction (as assessed by heart rate variability) is associated with the occurrence of GER events in neonates during sleep and wakefulness.

Methods

Nineteen neonates with suspected GER underwent simultaneous, synchronized 12-hour polysomnography and esophageal multichannel impedance-pH monitoring. We compared changes in HRV parameters during three types of periods (control and prior to and during reflux) with respect to the vigilance state.

Results

The vigilance state influenced the distribution of GER events (P<0.001), with 53.4% observed during wakefulness, 37.6% observed during active sleep and only 9% observed during quiet sleep. A significant increase in the sympathovagal ratio (+32%, P=0.013) was observed in the period immediately prior to reflux (due to a 15% reduction in parasympathetic activity (P=0.017)), relative to the control period. This phenomenon was observed during both wakefulness and active sleep.

Conclusion

Our results showed that GER events were preceded by a vigilance-state-independent decrease in parasympathetic tone. This suggests that a pre-reflux change in ANS activity is one of the factors contributing to the mechanism of reflux in neonates.     

A DNA Metabarcoding Study of a Primate Dietary Diversity and Plasticity across Its Entire Fragmented Range

In tropical regions, most primary ecosystems have been replaced by mosaic landscapes in which species must cope with a large shift in the distribution of their habitat and associated food resources. Primates are particularly vulnerable to habitat modifications. Most species persist in small fragments surrounded by complex human-mediated matrices whose structure and connectivity may strongly influence their dispersal and feeding behavior. Behavioral plasticity appears to be a crucial parameter governing the ability of organisms to exploit the resources offered by new matrix habitats and thus to persist in fragmented habitats. In this study, we were interested in the dietary plasticity of the golden-crowned sifaka (Propithecus tattersalli), an endangered species of lemur, found only in the Daraina region in north-eastern Madagascar. We used a DNA-based approach combining the barcoding concept and Illumina next-generation sequencing to (i) describe the species diet across its entire range and (ii) evaluate the influence of landscape heterogeneity on diet diversity and composition. Faeces from 96 individuals were sampled across the entire species range and their contents were analyzed using the trnL metabarcoding approach. In parallel, we built a large DNA reference database based on a checklist of the plant species of the Daraina region. Our results suggest that golden-crowned sifakas exhibit remarkable dietary diversity with at least 130 plant species belonging to 80 genera and 49 different families. We highlighted an influence of both habitat type and openness on diet composition suggesting a high flexibility of foraging strategies. Moreover, we observed the presence of numerous cultivated and naturalized plants in the faeces of groups living in forest edge areas. Overall, our findings support our initial expectation that P. tattersalli is able to cope with the current level of alteration of the landscape and confirm our previous results on the distribution and the dispersal ability of this species.     

Behavioural Profiles in Captive-Bred Cynomolgus Macaques: Towards Monkey Models of Mental Disorders?

Background

To date, experimental and preclinical studies on neuropsychiatric conditions have almost exclusively been performed in experimentally-induced animal models and have only rarely relied upon an ethological approach where animals have been observed in more naturalistic settings. The laboratory species of choice has been the rodent while the potential of more closely-related non-human primates have remained largely underexplored.

Methods

The present study, therefore, aimed at investigating the possible existence of spontaneous atypical/abnormal behaviours displayed by 40 cynomolgus macaques in captive conditions using an unbiased ethological scan-sampling analysis followed by multifactorial correspondence analysis and a hierarchical clustering.

Results

The study identified five distinct profiles (groups A to E) that significantly differed on several behaviours, body postures, body orientations, gaze directions and locations in the cage environment. We suggest that animals from the low n groups (D and E) present depressive-like and anxious-like symptoms, reminiscent of depressive and generalized anxiety disorders. Inter-individual differences were highlighted through unbiased ethological observations of spontaneous behaviours and associated parameters, although these were not associated with differences in plasma or cerebrospinal fluid levels of either stress-related hormones or monoamines, i.e. in accordance with the human situation.

Conclusions

No interventional behavioural testing was required to discriminate between 3 typical and 2 atypical ethologically-defined behavioural profiles, reminiscent of certain depressive-like and anxiety-like symptoms. The use of unbiased behavioural observations might, thus, allow the identification of animal models of human mental/behavioural disorders and their most appropriate control groups.